1. Field of the Invention
The invention relates to an MR method for determining the position of at least one microcoil which is provided in or on an object to be examined which is situated in an examination zone, at least one variable magnetic gradient field acting on the examination zone during the acquisition of microcoil MR signals so that the k space is scanned at scanning points.
In this context a microcoil is to be understood to mean a coil which can pick up MR signals only from a volume which is small in comparison with the overall examination zone. In order to distinguish the MR signals picked up by the microcoil from other MR signals, for example MR signals detected by means of a receiving coil system in order to determine the nuclear magnetization distribution in the examination zone, they are referred to as microcoil MR signals. MR stands for magnetic resonance. The k space is to be understood as the spatial frequency domain which is scanned at scanning points by variation of the magnetic gradient fields.
2. Description of Related Art
An MR method of the kind set forth is known from EP-A 731 362, which corresponds to U.S. Pat. No. 5,644,234. Therein, the k space is scanned at scanning points which are situated on radial paths extending through the zero point of the k space. The position of the microcoil is determined by frequency analysis of a microcoil MR signal in that the maximum of the spectrum of a microcoil MR signal (i.e. the Fourier transform of the microcoil MR signal) is determined. However, this MR method is limited to applications involving radial scanning of the k space and, moreover, necessitates calculation of the Fourier transforms of microcoil MR signals.